Transmission of HIV to Women

In the United States, most women are infected with HIV during sex with an HIV-infected man or while using HIV-contaminated syringes for the injection of drugs such as heroin, cocaine, and amphetamines. Of the new HIV infections diagnosed among women in the United States in 2004, CDC estimated 70 percent were attributed to heterosexual contact and 28 percent to injection drug use.In this country, studies have shown that during unprotected heterosexual intercourse with an HIV-infected partner, women have a greater risk of becoming infected than uninfected men who have heterosexual intercourse with an HIV-infected woman. In other parts of the world, however, this is not necessarily true. In Uganda, for example, one study demonstrated that the risk of HIV transmission from woman to man was the same as from man to woman. This difference may be due to the lack of circumcision in Ugandan men.Studies in both the United States and abroad have demonstrated that STIs, particularly infections that cause ulcerations of the vagina (for example, genital herpes, syphilis, and chancroid), greatly increase a woman's risk of becoming infected with HIV. NIAID-sponsored cohort studies in the United States have also found a number of other factors to be associated with an increased risk of heterosexual HIV transmission, including alcohol use, history of childhood sexual abuse, current domestic abuse, and use of crack/cocaine.Consistent and correct use of male latex condoms greatly reduces the risk of becoming infected with HIV. In studies of heterosexual couples, in which one individual was HIV positive and the other uninfected and regular condom use was reported, the rate of HIV transmission was extremely low.